The present invention relates to extendible tree trimming apparatus and particularly to such apparatus which is adapted to be manually manipulated.
Trimming of trees often requires removal of limbs from the upper and top portion of the tree, which are not readily and safely accessible from ground level without use of ladders or the like. Climbing of the tree with cutting equipment, particularly power equipment, is not only inconvenient but hazardous. Professional and commercial tree trimmers generally use truck-mounted power equipment having cutting devices which can be extended upwardly into the tree for remote cutting of limbs from within the tree. Smaller portable and manually manipulated tree trimming devices have been suggested for use by the owner and others in trimming of trees. For example, U.S. Pat. No. 3,715,805 which issued on Feb. 13, 1973 and is entitled "Tree Pruning Saw" discloses a multiple section tree trimmer for varying the length of the device. A motor at the lower end is coupled through a drive shaft mechanism to a cutting blade mechanism at the upper end. U.S. Pat. No. 4,654,971 which issued on Apr. 7, 1987 and is entitled "Pruner With Collapsible Drive Shaft And Housing" also discloses an extendible telescopic multiple section tree trimming apparatus. The structure of this latter part includes an outer telescopic housing unit and an inner telescopic drive shaft unit permitting extension and collapse of the tree trimming apparatus. A locking means allows setting of the unit in the various adjusted extended position. The patent particularly discloses a single sliding sleeve bearing floating between the telescopic housing unit and the telescopic shaft unit to provide a complete separation of the extendible housing and drive shaft sections or units. Other extendible cutting devices have been suggested and are discussed in the above prior art.
The extendible nature of the apparatus requires special consideration be given to the coupling of the sections to provide a long reliable and operative life. In addition, providing a proper transmission of the torque from the power source at the lower end of the extendible tree trimming apparatus to the remotely located cutting apparatus is also significant in order to provide an effective tree trimming apparatus. The transmission of the torque from an electric or gas motor to the cutting apparatus must, for example, include an efficient power transfer to permit use of a relatively small compact power source which in turn permit convenient manual handling of the tree trimming apparatus. In addition for effective transfer of power to the upper cutting head, translation of the rotary shaft unit to movement of the cutting mechanism must be efficient, reliable and have a long operating life, with minimum service and maintenance requirements. Although the end user may have certain skills and capabilities, the user often tend the use the equipment without giving due consideration to servicing of the equipment until the equipment malfunctions or fails.
There is therefore a distinct need for an efficient and long life tree trimming apparatus which is lightweight for convenient manual manipulation while providing effective and efficient cutting at the remote end of the tree trimming apparatus.